Water-soluble polymeric films are commonly used as packaging materials to simplify dispersing, pouring, dissolving and dosing of a material to be delivered. For example, water-soluble unit dose articles made from water-soluble film are commonly used to package household care compositions, e.g., a pouch containing a laundry or dish detergent, and non-household care compositions, e.g. a pouch containing a water treatment active agent. A user (e.g., a consumer) can directly add the water-soluble unit dose article to a mixing vessel, such as a bucket, sink or washing machine, or to the water tank of a toilet, or to a swimming pool. Advantageously, this provides for accurate dosing while eliminating the need for the consumer to measure the composition. The water-soluble unit dose article may also reduce mess that would be associated with dispensing a similar composition from a vessel, such as pouring a liquid laundry detergent from a bottle or dispensing water treatment granules or pellets from a bucket. The water-soluble unit dose article also insulates the composition therein from contact with the user's hands. In sum, water-soluble unit dose articles containing pre-measured agents provide for convenience of consumer use in a variety of applications.
Some water-soluble polymeric films that are used to make water-soluble unit dose articles will incompletely dissolve during a wash cycle, leaving film residue on items within the wash. Such problems may particularly arise when the water-soluble unit dose article is used under stressed wash conditions, such as when the pouch is used in cold water (e.g., water as low as 5° C. and/or up to 10° C. or 15° C.), with short water contact times, e.g. in a short wash cycle, and/or with low concentrations of water available for film dissolution, e.g. in a low-water wash cycle (e.g., wash liquors from about 3 L to about 20 L for pouches sized to contain 5 mL to 300 mL contents, for example). Notably, environmental concerns and energy cost are driving consumer desire for utilizing colder wash water and shorter wash cycles in laundry applications.
Some water-soluble polymeric films that are used to make water-soluble unit dose articles will completely dissolve during a wash cycle but are so substantive to water that the films will become sticky when exposed to high humidity conditions, causing water-soluble unit dose articles made thereof to stick together when exposed to such high humidity conditions during manufacturing or upon storage in the container during transport, at a warehouse or in consumers' home.
Additionally, it is desirable for the water-soluble unit dose article to have an adequate strength, both soon after making and upon storage, to withstand forces that may be applied during packing, transport, storage, and usage. Adequate strength may be particularly preferred with the pouches encapsulate liquid compositions, such as laundry detergent or dye concentrates, to avoid unintentional bursting and/or leakage.
There remains a need for water-soluble films and water-soluble unit dose articles, such as pouches, having the desired characteristics of good water solubility, reduced sticking, suitable pouch strength, chemical resistance, chemical and physical compatibility with laundry actives or other compositions in contact with the film or water-soluble unit dose article formed therefrom, and/or desirable mechanical properties, such as deformability upon thermoforming and/or adequate sealing. It has been found that water-soluble unit dose articles according to the present disclosure exhibits optimal water solubility and reduced stickiness.